Tomas Vampola 1 , Anne-Maria Laukkanen 2 , Jaromir Horáček 3

1 CTU in Prague, Department of Mechanics,Biomechanics and Mechatronics, Prague

2 University of Tampere, Department of Speech Communication and Voice Research, Tampere

3 Institute of Thermomechanics, Academy of Sciences of the Czech Republic, , Prague

Phonation into a tube is widely used as a vocal exercise or therapy method, which typically causes immediately at least temporary improvement in voice quality, higher loudness and sensation of ease of phonation. Story et al. [1] and Titze & Laukkanen [2] theoretically studied changes of the input acoustic impedance of the vocal tract prolonged by the tubes of various geometries in relation to the phonation fundamental frequency. An optimized regime was found when the fundamental frequency was less than first formant frequency in the range where the acoustic reactance is positive and of a high level.

The present paper compares the geometry and acoustic characteristics of the supraglottal spaces before, and immediately after phonation into the tube, based on CT scanning of a female subject and finite element (FE) modeling. The subject sustained vowel [a:] and phonated into a glass tube (inner diameter 7 mm, length 27.5 cm). Fundamental frequency varied between 156-176 Hz. Each CT measurement took about 4s when 181 images of 0.625 mm slice thickness with overlaying 0,984:1 were taken. By the segmentation procedure used for each image and after the 3D reconstruction the volume model of the vocal tract was developed first. After meshing, the 3D FE model of a very high quality, comparing to the previously developed models based on MRI measurement [3], was created.

Preliminary analysis shows that after phonation into the tube the volume of the acoustic spaces of the vocal tract increased of about 20%, and the cross-sectional areas of the vocal tract spaces in the epilarynx and in the mouth cavity increased up to about 10%. An opposite tendency was possible to identify in the laryngeal part just above the vocal folds, where the cumulative cross-sections, covering also the piriform sinuses, slightly decreased after the exercise. The results from both the acoustic analysis of the sound records, taken during the CT measurement, and from the acoustic frequency-modal analysis of the FE models suggest that the lowest formant frequencies differed just slightly before and after the exercise. The first and second formant frequencies decreased about 6% and the third formant increased about 7%. Additionally, the velum closure improved after the exercise.

In both FE models before and after the voice training there are relatively large piriform sinuses and additional acoustic spaces near the epiglottis (valleculae). Higher acoustic mode shapes are associated with internal resonances of these spaces where a 3D character of the modes dominates.

•[1]        Story B.H., Laukkanen A.M., Titze I.R. (2000): Acoustic impedance of an artificially lengthened and constricted vocal tract. Journal of Voice, Vol. 14, No. 4, 455-469

•[2]        Titze I.R., Laukkanen A.M. (2007): Can vocal economy in phonation be increased with an artificially lengthened vocal tract. A computer modeling study. Logopedics Phoniatrics Vocology, Vol. 32, 147-156.

•[3]        Vampola T., Horáček J., Švec J.G. (2008) FE modeling of human vocal tract acoustic. Part I: Production of Czech vowels. Acta Acoustica United with Acta Acustica. Vol. 94, 433-447.

 

Isao Tokuda 1 , Malte Kob 2 , Hanspeter Herzel 3

1 JAIST, School of Information Science, Nomi-city

2 University of Music Detmold, , Detmold

3 Humboldt University of Berlin, , Berlin

The exact definition of registers in the human voice is still under debate. Especially the quantitative analysis of transitions between the registers has not been investigated in much detail yet. Excised larynx experiments show different kinds of voice instabilities that appear close to the transition from chest to falsetto register. Similar phenomena are also observed in vocalization of untrained singers. Towards comprehensive understanding of such register transitions, biomechanical modeling and bifurcation theory are applied. Our model has a body-cover structure, which is in total composed of fourth masses. A smooth geometry is realized by introducing a polygon shape to the vocal fold model, which reproduces characteristic features of chest and falsetto registers. Sub- and supra-glottal resonances are also modeled using a wave-reflection model. Simulations for increasing and decreasing  the subglottal pressure reveal that the phonation onset exhibits amplitude jumps and hysteresis referring to a subcritical Hopf bifurcation. The onset pressure is reduced due to the vocal tract resonances. Hysteresis is observed also for the voice breaks at the chest-falsetto transition. Varying the length of the subglottal resonator has only a minor effect on this register transition. Contrarily, supraglottal resonances have a strong effect on the pitch, at which the chest-falsetto transition is found.

Anne-Maria Laukkanen 1 , Jaromir Horacek 2 , Petr Krupa 3 , Jan Svec 4

1 University of Tampere, Dept. of Speech Communication and Voice Research, Tampere

2 Institute of Thermomechanics, Academy of Sciences of the Czech Republic, , Prague

3 St. Anne's Faculty Hospital, Masaryk University, Department of Medical Imaging, Brno

4 Palacky University Olomouc, Laboratory of Biophysics, Dept. Experimental Physics, Olomouc

Phonation into a tube is a well-known voice training and therapy method.

Using magnetic-resonance imaging (MRI) technique this study aimed to investigate the effects of this exercise on the vocal tract configuration both during and after phonation into a plastic soda straw (15 cm in length, 5 mm in inner diameter). A female subject with no voice or hearing problems and with extensive experience in voice training phonated in supine position twice on vowel [a:], twice into the tube and then again twice on [a:].

According to the results, during phonation into a tube (compared to [a:]) the size of the vocal tract increased in diameter and partially also the length of the vocal tract changed slightly. The distance from the vocal folds to the anterior arch of Atlas decreased by 4.2 % and that from the arch to the lips increased by 5.1 %. The greatest changes in diameter took place in the mouth cavity (22 % between the tongue and palate and 103 % between the tongue tip and alveolar ridge), which obviously reflects the fact that the vocal tract adopted the shape for producing vowel [u:]. The vocal tract remained wider (especially in the front part of the mouth cavity, 21 % and 54 %) also in [a:] after the tube compared to [a:] produced before phonation into a tube, however the difference in length was very small (0.2 and 0.4 %). The adjustments of the vocal tract during phonation into a tube, especially widening of the upper vocal tract, thus, seem to remain to some extent also in vowel phonation after the tube. The velar closure also improved after phonation into the tube.

It was not possible to measure reliably any differences in the size of the epilaryngeal region (piriform sinuses, laryngeal ventricle and the space between the false vocal folds) in the MRI recordings.

The results will be discussed from the point of view of aims in voice training.

Claudio Storck 1 , Philipp Juergens 2 , Franz Ebner 3 , Erich Sorantin 4 , Markus Wolfensberger 1 , Gerhard Friedrich 5 , Markus Gugatschka 5

1 University Hospital Basel, ENT-Department, Basel

2 University Hospital Basel, Hightech Research Center, Basel

3 University Hospital Graz, Department of Neuroradiology, Graz

4 University Hospital Graz, Department of Radiology, Graz

5 University Hospital Graz, ENT - Department, Graz